Mixtures of linear polyaryl-ether-sulphones and polycarbonates have already been described (see DT-OS (German Published Specification) No. 1,719,244 and U.S. Pat. No. 3,365,517); their use for the production of films has also already been described (Page 21 of DT-OS (German Published Specification) 1,719,244).
These mixtures are said to overcome, on the one hand, the undesired embrittlement of the polyaryl-ether-sulphones under load and, on the other hand, the susceptibility of the polycarbonates to stress-cracking in the presence of solvents (Page 2 of the DT-OS (German Published Specification)).
Mixtures of this type can be used for the production of cast films (Examples 8 and 9 of the DT-OS (German Published Specification) and 14 and 16 of the U.S. Patent Specification). The polycarbonates which are customarily suitable for injection-molding and extrusion, the Mw of which is, for example, about 35,000, are given as polycarbonates in the literature references mentioned (Example 2 of the DT-OS (German Published Specification)). However, films of mixtures of this type have a strong tendency to stress-cracking.
If the polycarbonate component with a Mw of 35,000 described in DT-OS (German Published Specification) 1,719,244 and U.S. Pat. No. 3,365,517 is replaced by a high-molecular polycarbonate which cannot be extruded without a decrease in the molecular weight, and cast films are produced from mixtures of this type, these products also exhibit a strong tendency to stress-cracking as well as inadequate mechanical properties.